Apparatus for maintaining a predetermined water level in steam boilers



,Nov. 1 8, 1930.

G. H. DAVIN APPARATUS FOR MAINTAINING A PREDETERMINED WATER LEVEL IN STEAM BOILERS 2 Sheets-Sheet 1 lnvouhr Com Hannah Down Nov. 18, 1930. G, H. DAVIN APPARATUS FOR MAINTAINING A PREDETERMINED WATER LEVEL IN STEAM BOILERS Filed May 18, 1928 Sheets-Sheet 2 PISA- FICiQ- Hun H. 174717! I. yr

@M8 5 ME 7 @0011 Hemcll 04v Patented Nov. 18, 1930 UNITED STATES PATENT I. OFFICE GEORGE HEINRICH DAVIN, OF OASSEL, GERMANY, ASSIGNOR TO SCHMIDTSCHE HEISS-r DAMPF G. M. B. H., OF CASSEL-WILHELMSHOHE, GERMANY, A CORPORATION OF GERMANY APPARATUS FOR MAINTAINING A IPREDETERMINED WATER LEVEL IN STEAM BOILERS Application. filed May 18, 1928, Serial No.

This invention relates to apparatus. for

steam boilers, particularly those of the type in which a substantial part of the boiler volume is to be utilized for steam generation and storage, and in which the pressure and water level are constantly fluctuating due to temorar r overloads. In carrvin out the ine u D vention, a device which regulates the admission of feed water to the boiler is positioned in a regulating chamber which is located in a line between the boiler and feed water suction pipe. The functioning of this regulating device depends on whether steam or water passes through the regulating chamber.

The invention consists primarily in a throttling or choking device in the form of a labyrinth stutling box contained in the regulating chamber. Through this stuffing box only a very small weightquantity) of steam can pass which condenses in the labyrinth grooves and appears at the other end in liquid form. This small quantity of condensed material can pass freely through a second throttling means which is located beyond the regulating chamber. If, however, the surface of the water in the boiler rises to such a height that it flows directly into the lal'wyrinth stalling box, a great quantity of water will flow into the regulating chamber due to the well known fact. that a stutiing box of this nature oflers very much less resistance to the passage of water than to steam at the same pressure. In consequence the pressure in the regulating chamber becomes relatively high, the regulating device will be displaced and the admission of feed water to the boiler might be stopped altogether. The present invention now possesses the advantage that a considerable difference of pressure is avail able with which to operate the regulating means. A further advantage lies in the fact that the loss of heat is very small because of the small flow of steam through the grooves of the labyrinth stufiing box.

A particularly advantageous construction of the regulating means of the present invention is obtained by so constructing the plunger which regulates the flow of feed water that it will serve at the same time as a throttling 278,834, and in Germany July 11, 1927.

means. To accomplish this the regulating iston does not fit tightly into the cylinder ore in which it is arranged to move, but enough clearance (play) is left so that the flow of. water will be impeded but not totally prevented.

One embodiment of my invention is illustrated in the accompanying drawings, in which: a

Figure 1 shows, somewhat diagrammatically, the complete organization of elements.

Figure 2 shows on a larger scale a vertical section of the regulating chamber and its two throttling means.

Figure 3 is a cross-section on line 3-3 of Figure 2.

Figure 4 shows the lower throttling means of Figure :2 on a still larger scale; and

Figure 5 shows a cross-section on 55 of Figure 4 as seen from below.

In Figure l the numeral 1 designates a boiler whose normal water level 2 it is the object of this invention to maintain. A pi e 3 provided with a valve 21 leads from t e boiler at the Water level to the first throttling means in the regulating chamber. The

pipe 13 leads from the boiler to the steam engine 14 which drives the feed pump 15. Pipe for controlling the feed water supply term a unitary structure whose housing consists of two parts. The upper part :22 contains the labyrinth throttle (see Figures 2 and 3) which consists of conically formed pieces 23, 24, 25, 26 whose contacting conical surfaces are provided with spirally arranged grooves which form continuous labyrinth throttle passa es. The outer cone 23 has its u per rim 2! supported by the upper edge 0L the housing 22 and it is held in place by a cover 28 which in turn is connected with a flange 29 forming part of the housing 22, by means of bolts 30. The pipe 3 passes through the cover 28. Between the cover 28 and the inner conical member 26 there is arranged a helical spring 31 whose object it is to keep the several sition their upper edges form with the cover 28 a space 32 having a stepped inner peripheral surface, and these conical pieces project with their lower ends in ste formation into a space 33 at the lower en of the housing 22. This space 33 constitutes the actual regulating chamber. The annular flange 34 formed at the lower end of the housing 22 is, by means of bolts 37, detachably secured to a corresponding flange 35 at the upper end of a cylinder 36. Between the two flanges 34, 35 there is clamped an intermediate plate v 38 formed with a semispherical bulge 40,

which bulge is provided with an opening 39 at its peak. In the cylinder 36 is movably positioned a regulating piston 41 the construction of which is such that a small clearance (Figure 4) is left between the piston and the wall of the cylinder 36. The bodyof this cylinder is constructed in the form of a so called lantern frame. The bore 42 of the cylinder is closed at its lower end by means of a bushing 43 threaded into the cylinder, and a stuffing box 44 within the bushing.

The lower end of the busihng 43 which projects into the open space of the lantern-like frame of the cylinder 36 has the form of a hexagonal nut 45 (Figure 5). A key (Wrench) 47 having a rin like end (46) is positioned on'thisnut an is locked in ad- 1ustedposition by the screw'48;-- The lower end 49 of the frame is provided with a transverse passage 50 to the two ends of which the steam pipe 13 leading to the c linder 14 is joined. Through the hole 50 t e lower end 51 of the (piston rod 52 projects, this rod be;

ing guide not only by the stufiing box 44 but also by a second stufling box 53 mounted in the lower part of the frame 49. Within the cylinder bore 42 there is a helical sprin 54 mounted on the piston rod 52 which ten s to hold the regulating piston 41 in its upper position 1n which position the steam pipe 13 is open. From the lower end of the cylinder bore 42 the drain pipe 18 leads to the suction pipe 16 to which it is connected. The drain pipe 18 comprises a throttle'valve 55 and also a sight glass 56.

It is a well known fact that if water passes through a throttling aperture, theweight in a given time exceeds by many times the weight of steam which could pass through the same aperture, if the pressure drop across the aperture is ual in 0th cases. With a pressure drop 0 approximately 12 atmospheres, the ratio of the weights of steam and water passing through the aperture is about The operation is as follows: \Vhen the level of the water in boiler 1 lies below the opening of the pipe 3, steam will flow through the latter through the labyrinth throttle device in whose passages it is condensed, losing its pressure 1n so doing. Since but a small quantity of steam can pass through the throttle device a correspondingly small quantity of water willbe discharged under no pressure and iniitlie form of drd'ps from the lower end of the throttle device into the space pipe 18. This condenser water because of its slight weight will exert no pressure or in any case very little pressure on the regulating piston 41 so that the spiral spring 54 will not be compressed and the piston will remain in its highest position, in which case the steam passes freely through the pipe 13 to the steam chest of the feed pump engine 14. In this condition the maximum amount of water is fed into the boiler.

When the water level in boiler 1 rises above thepipe 3 water, in addition to steam, will be conducted to the labyrinth throttle. Since the resistance of the latter to. thevpassage of water"is"much less ,than to that-fof steam,

more water will pass -througl1 and its weight will force the regulating piston partially down and the passage of steam through pipe 13 will be throttled. Finally, when nothing but water passes "through the labyrinth throttle, the full boiler pressure diminished by the frictional resistance in the labyrinth throttle will force down the plunger and the admission of steam will be cut off altogether. As soon as the water level goes down again to normal the pressure on the regulating piston will be removed.

By means of the valve 21 the flow of the steam through pipe, and by means of valve 55 the flow of water through pipe 18, can be regulated. In this way the operation of the wholeq'egulating device can be so adjiistcd that it functions continuously, i. 0., without great inter-missions. In order that but little steam may be condensed in the labyrinth throttle, the housing should be covered with heat insulating means. Since but little steam is condensed the formation of scale, when hard water is used, .will be comparatively small and the danger of the stopping up of the various passages is correspondingly small. By means of the sight glass 56 the operation of the device can: be observed, and in case of scale-forming feed water it can be seen how far the obstructing of the steam and water passages has been advanced.

The construction of the whole device is very simple and admits of eas taking apart for the purpose of cleaning; t is only necessary to loosen the union joint helowthevalve 21 and to remove the bolts 30 from the flange 29and to remove the cover'in order to make the labyrinth throttle accessible... The conical member can then easily beremoved' and then be separated by knocking at their lower step-like arrhngetl sends. In equally easy manner the piston 41 can be taken out by removing the bolts 37. The pressure of the spring 54 on the piston 41 can be regulated while the apparatus is in operation by means of the wrench 47. The lantern shape of the housing and the ring formation of the wrench allow a removal of the wrench, a remounting of the wrenchin a new position, and the turning of the same. After the adjustment has been made the stufiing box 43 will be locked in its positionv by the screw 48 passing through the wrench into the cylinder 36.

While I have shown and described the preferred embodiment of my invention, I wish it' to be understood that various changes in the construction and arrangement of parts may be made, limited only by the scope of the appended claims.

hat I claim is:

1. Apparatus for maintaining a predeter mined water level in a steam boiler comprising a drum'containing'water and steam, a feed pump for maintaining a water level in the drum, a steam supply line to said feed pump, a throttling device in said supply line, and means inserted between the drum and the feed line of the pump for controlling said throttling device, said means comprising a chamber, a lab rinth throttle having passages ing formed of a plurality of detachable parts. g I

5. A device as claimed in claim 1, having a spring pressing said plunger toward said throttle, and means for adjusting the tension of saids ring? 6. A evice as claimed in claim 2, a bushing for closing the lower end of said chamber screw-threaded in the wall of said chamber, a spring supported by said bushing below said plunger and acting on said plunger, the end of said bushing having-the form of a nut, a wrench adapted tofit on said nut, and means for securin said wrench to the lower wall of said cham er.

7. A device as claimed in claim 1, said throttle comprisinga plurality of telescoping frustro-conical members having helical grooves in the outer side thereof extending from end to end, the smaller ends ofthe frustro-conical members being stepped, the end of the central frustro-conical member extending beyond the end of the adjacent frustro-conical member.

8. In a device of the character described, means for controlling the flow of steam to a feed pump which feeds water to a boiler comprising a chamber, a labyrinth throttle at one end thereof adapted to connect said chamber to said boiler at a desired water level, and a pressure operated plunger communieating with the chamber adjacent said throttle and connected to said-throttle, said plunger controlling the supply of steam to said a feed pump.

In testimony whereof, I have hereunto set my signature.

GEORGE HEINRICH DAVIN.

of considerabe length at one end of said chamber and. a pressure operated plunger communicating with the chamber adjacent said throttle and connected thereto.

'2. In combination with a steam boiler and feed pump therefor, a device for controlling the operation of the feed pump to maintain a. substantially constant water level in the boiler drum, said device comprisin a chamber having a connection with the rum at a selected water level, a labyrinth throttle having passages of considerable length at one end of said chamber for impeding the passage of steam whilea llowing water to pass therethrough, a lunger within the other end 1 ofsaid chamber avingra slightrclearanceyfor permitting the passage of a limited amount of water, a drain beyond said plun er, andmeans controlled by said plunger or regulating the steam supply to the feed water- Pu p- 3. A device as claimed in claim 1, said chamber, throttle and plunger being contained in a single housing.

4. A device as claimed in claim 1, said chamber, throttle and plunger being contained in the same housing, said housing be- 

